Apparatus for forward beamforming using feedback of multipath information and method thereof

Abstract

Disclosed are an apparatus for forward beamforming using a terminal feedback and a method thereof. The base station estimates an angle of arrival (AOA) range of a user signal from reverse link received data and calculates a plurality of beamforming weights steering the estimated AOA range. Then, the base station transmits a user pilot signal by sequentially using the plurality of beamforming weights at different time areas through a control channel to estimate a forward channel conditions. A terminal calculates the user pilot signal power for all fingers at the respective time areas and feeds a time area number corresponding to the greatest power back to the base station. The base station transmits a data channel signal using a beamforming weight corresponding to the time area number fed back from the terminal.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a divisional of U.S. Ser. No. 10 / 025,780, filed on Dec. 26, 2001. This application, in its entirety, is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention relates to an apparatus for forward beamforming using a feedback of multipath information and a method thereof; and, more particularly, to an apparatus for forward beamforming using a feedback of multipath information, which is used in a frequency division duplex (FDD) code division multiple access (CDMA) base station system that uses an array antenna, and a method thereof. DESCRIPTION OF RELATED ART [0003] A mobile communication base station system using an array antenna increases an antenna gain with respect to a desired user to increase a maximum range, and decreases the antenna gain with respect to a user disposed at different angles to reduce an interference signal, thereby increasing a system capacity. [0004] A typical code di...

AI Technical Summary

Benefits of technology

The present invention provides an apparatus and method for forward beamforming in a mobile communication system using an array antenna. The apparatus includes an arrival angle range estimation means, an array receiver and demodulation means, a forward beamforming weight control means, and a forward beamforming and modulation means. The method involves estimating the angle of arrival of a user signal, calculating a plurality of beamforming weights, transmitting a pilot signal, identifying a time area number, and transmitting a data channel signal using the selected beamforming weight. The invention allows for effective data communication by selecting the best channel condition among several directions using the feedback information from the terminal.

Problems solved by technology

However, there is a problem that a reverse link performance is degraded because a feedback data rate is increased in order to track a rapidly varying channel vector for a user moving fast.

However, there is a problem that a rapidly varying fading coefficient cannot be considered and so a calculated beamforming weight vector is not optimum at every time instant.

Although this method has an advantage that the forward channel property can be estimated only with the reverse link data, a time delay becomes increased due to a long averaging time.

Also, this method is difficult to be directly applied for the non-moving terminal.

In addition, since this method utilizes the average property of the channel, it cannot consider the instantaneously changing fading coefficients and so a fading reduction effect cannot be expected in the forward link.

This method requires a significantly lower feedback data rate than the full feedback method (the first method), but it is based on the assumption that there is no angle spread in the channel and so cannot be directly applied for the channel with high angle spread.

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